The Observer Pattern

A beginner-friendly walkthrough of the Observer design pattern, implemented in Python. Covers the core concept of observable objects notifying registered observers when events occur, with a fun GoatDetector example. Includes two implementations: a simple single-event version using a list, and a more practical multi-event version using a dict to map event types to observer lists. Also touches on real-world use cases like GUI button events in ActionScript and async network data handling.